Bottles & Boobs

How to Know if Baby Formula Doesn’t Agree With Your Infant?


by Bridget Reed, Milk-Drunk Contributor

Many new parents and even seasoned parents often wonder how to know if formula doesn’t agree with your baby. The need to know may arise for a few reasons, firstly it may be as a preventative measure, as well as it may be the need to solve an existing issue. 

We want to help you pinpoint what works or does not work for your baby. As well as a general view of possible symptoms that may occur in cases where the formula you are using does not work well for your baby. You will also see notation regarding contacting your pediatrician both for preventative cases as well as post cases. 

When it comes to choosing formulas for your baby, you always want to ensure that you choose the very best formula from a brand that you trust. The ingredients that go into the formula matters for the health of your baby. 

The FDA has strict regulations surrounding the ingredients and nutrients that must be present in infant formula. All infant formula regardless of the brand must contain the minimum nutrient requirements. 

What are some baby formula options?

In terms of formula choice, there are a few to choose from. You may find infant formula in three main ways: powered, and liquid concentrate which must be mixed with water safe for drinking, and ready-to-use which is as it says. Ready to use, no mixing needed. 

You may get these in your choice of base ingredient:

Cow’s milk formula- As the most common infant formula base, this type of formula is beneficial in helping protein to be more digestible. They are usually iron-fortified, so your baby will get the required amounts from this type of formula. While this type of formula is often easily digestible some babies may be allergic to some proteins found in cow’s milk.  This type is most common in cases where formula may not agree with your baby. You can typically find this in conventional and organic forms but some companies may have grass-fed cow’s milk options. 

Soy formula- This type of formula is a vegan option that is often recommended in cases of allergy to cow’s milk. It is also used because of dietary preference. This comes in conventional and organic forms. 

Protein hydrolysate formula- This type of formula contains proteins that have been broken down making them even more digestible.  It is commonly used or recommended in cases where babies have an intolerance to cow’s milk and even soy-based infant formulas.  

However, even if you get the very best product available, it may not agree with your baby. Here, the only sure thing is buying what you perceive as the best both from personal research as well as the recommendation of someone you trust with your child’s health such as a pediatrician and giving it a try. 

Using a Feeding Journal 

One of the best ways to know if the formula you are using doesn’t agree with your baby is to keep track. We all know that what works well in one baby may not work well in others. This is simply a part of life. 

If this is preventive research for you, it may be a good time to get a feeding journal. If you are here conducting research to solve then you can also begin this practice. 

With a feeding journal, you will be able to note your baby’s response before feeding, when you are feeding, the amount of formula used (ensure that it is within the guidelines recommended by the brand you choose), as well as the way your baby responds after feeding. 

By closely monitoring your baby and keeping track, you may be able to pinpoint how the baby is feeling as well as possible symptoms that you are noticing. 

But, what do the symptoms mean, and which ones may indicate an issue? 

A Guide to Common Symptoms 

Many things may cause a baby to respond negatively to baby formula. Some may directly relate to the baby formula such as food allergies, a need for more iron, or the formula just doesn’t feel good to your baby resulting in fussiness or diarrhea.

However, it is important to note that there may be other things occurring that do not directly relate to the formula yet they present similar symptoms to a formula reaction.

When it comes to responses to baby formula or just caring for your baby in general, there are some common symptoms that may indicate an issue.  However, apart from general observation and recording what you notice a good practice to develop is contacting your pediatrician should you feel concerned. 

Per the research available here are some common symptoms you may notice when the baby formula doesn’t work well for your baby :

Diarrhea- Pinpointing diarrhea in babies can sometimes be difficult and it may or may not be directly related to the formula. If you notice an increase in loose stools, more that you normally see then this could be an indication. Record your observances and share your concerns with your pediatrician.   

Extra Gas- Gas is quite common and in fact normal for infants. Extra gas may be pinpointed if the baby seems to have difficulty passing gas. It is important to note that extra gas in infants can be caused by many things formula and non-formula related. One example of a non-formula related cause of extra gassiness is feeding positions. Again, best practice is to record your observations and share your concerns with your pediatrician.   

Extra fussiness- Like the others, some fussiness is common and quite normal. Use your judgment in telling if your baby seems fussier than usual, especially after feeding. It’s always a good idea to share your concerns with your pediatrician.  

Dry, red skin- You will be able to see if your baby has developed any redness or dryness of the skin. Sometimes an allergic reaction to the baby formula may be the cause. However, sensitivity to clothing or other may cause this as well. Record what you are noticing and give your pediatrician a call. 

If you notice any of the above, these are important things to note in your log. You may also note information about your baby formula such as type, ingredients, expiration dates, and so forth. Once you get in contact with your doctor, you should have all the necessary information on hand. 

Changing your baby formula

If you have been noticing and recording the happenings with your baby and you think it may be due to the infant formula, it may come to your mind to change the formula. 

However, it may not be the best choice unless you have spoken to your family doctor or pediatrician first. The reason being, it may be the formula causing the things you are noticing but you may not know exactly why. Switching to another formula without receiving more direct information relating to your baby specifically may not solve the problem. 

No two formulas are alike but you may want to still ensure that you do not experience the same issues after switching. So, double-check and speak to your loved one and trusted caretaker before making a switch.


You may be new to this, we get it and respect it! And, so is your baby. Your baby is new to feeding on their own in this big new world and so it is common that you have minor hiccups along the way. 

So, how to know if formula doesn’t agree with your baby?. There is no definitive way for you to know this on your own. What you can do is monitor your baby, record your notices, and share them with the professionals you trust with the health of your baby. 

All in all: 

  • Try to select the best formula for your baby by doing proper research and using the information that is available to you. 
  • Closely monitor the baby and yourself once you begin feeding, whether breastfeeding or formula feeding.
  •  Keep a log of feeding times, responses, possible symptoms, and just a general view of your baby’s feeding habits. This is a good practice to develop, even for yourself.
  • Reach out to your pediatrician whenever you notice something off – and you will have all the information from the log as your guide. Do not hesitate here, or second, guess yourself. Asking questions is a good way to find something out.
  • Trust the process, you are doing amazing!  
The content on this site is for informational purposes only and not intended to be a substitute for professional medical advice, diagnosis or treatment. Discuss any health or feeding concerns with your infant's pediatrician. Never disregard professional medical advice or delay it based on the content on this page.

Meet the Author

Bridget Reed, contributing writer for Milk Drunk with the expert advice of Dr. Jacqueline Winkelmann

Bridget Reed is an experienced writer, editor SEO content manager and proud mom of three.

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